What is the atomic mass of the element that consists of the following isotopes in the indicated natural abundances?

Isotope Isotopic mass (amu) Rel. abundance (%)

A 57.93 67.76
B 59.93 26.16
C 60.93 1.25
D 61.93 3.66
E 63.93 1.16

Express your answer to 3 sig figs and include the appropriate units

Answer : The atomic mass of the element is, 58.70 amu

Explanation :

Average atomic mass of an element is defined as the sum of masses of each isotope each multiplied by their natural fractional abundance.

Formula used to calculate average atomic mass follows:

As we are given that,

Percentage abundance of isotope A = 67.76 %

Fractional abundance of isotope A = 0.6776

Percentage abundance of isotope B = 26.16 %

Fractional abundance of isotope B = 0.2616

Percentage abundance of isotope C = 1.25 %

Fractional abundance of isotope C = 0.0125

Percentage abundance of isotope D = 3.66 %

Fractional abundance of isotope D = 0.0366

Percentage abundance of isotope E = 1.16 %

Fractional abundance of isotope E = 0.0116

Now put all the given values in above formula, we get:

Therefore, the atomic mass of the element is, 58.70 amu

the answers would be

the first one and the second one